Smoke control in high-rise residential buildings with stair pressurization systems

Stair pressurization systems are designed to create a smoke-proof barrier, preventing the ingress of smoke into staircases within buildings. In tall buildings over 25 m, evacuation strategies can utilize phased or simultaneous evaluation of multiple storeys. This paper examines the performance of a stair pressurization with a differing number of doors open starting from two doors, with an incremental step of two up to a total of 10 doors into the shaft. Simulations using Fire Dynamics Simulation (FDS) have shown that a system that would pass commissioning requirements allows smoke in the shaft if there are more than four doors open simultaneously. The required airflow to prevent smoke ingress was found to be above an average flow speed of 0.7 m/s. Past this limit, the amount of smoke that leaks into the staircases continues to increase as more doors open. The study suggests that standards regarding stair pressurization systems should be updated to account for realistic evacuation scenarios, including the system’s cascade settings, number of storeys, and expected evacuation time, as evidenced by the smoke leakage once four doors were open and the drop-in flow rate between two-door and four-door open cases.